9th Class Chemistry Chapter No. 1 Fundamentals of Chemistry Notes
Science is the knowledge that provides us with a deep understanding of the world and its functioning. One of the branches of science that plays a crucial role in unraveling the mysteries of matter is chemistry. Chemistry is the study of the composition, structure, properties, and reactions of substances, and it touches every aspect of our lives.
The Impact of Chemistry in Our Daily Lives
The development of science and technology has bestowed upon us numerous facilities in our daily lives. Many products that we use regularly, such as petrochemicals, medicines, drugs, soaps, detergents, plastics, paints, insecticides, and pesticides, are the results of the relentless efforts of chemists. Chemistry’s influence is evident in various industries and aspects of our lives.
Long Questions Notes
However, it is essential to recognize that the growth of the chemical industry has also given rise to challenges like toxic waste, water contamination, and air pollution. As we enjoy the benefits of chemical advancements, it becomes crucial to responsibly manage the waste and by-products to protect our environment.
On the other hand, chemistry not only contributes to the problems but also provides solutions. It offers knowledge and techniques to improve human health, preserve the environment, and explore and conserve natural resources.
Short Answer Questions Notes
Branches of Chemistry
Chemistry is an expansive field, and it is divided into several specialized branches, each with its unique focus and applications. Here are some of the main branches of chemistry:
Physical Chemistry: This branch explores the relationship between the composition and physical properties of matter, including the behavior of gases, liquids, and solids. It also investigates the effects of temperature and radiation on matter.
Organic Chemistry: Organic chemistry deals with covalent compounds of carbon and hydrogen (hydrocarbons) and their derivatives. It is vital in understanding the structure and properties of naturally occurring and synthesized compounds.
Multiple Questions Notes
Inorganic Chemistry: Inorganic chemistry involves the study of all elements and their compounds, excluding hydrocarbons and their derivatives. It finds applications in industries such as glass, cement, ceramics, and metallurgy.
Biochemistry: Biochemistry delves into the structure, composition, and chemical reactions of substances found in living organisms. It plays a significant role in understanding biological processes, metabolism, and diseases.
Industrial Chemistry: This branch focuses on the large-scale manufacturing of chemical compounds, such as basic chemicals used in various industries, including fertilizers, textiles, and paper.
Nuclear Chemistry: Nuclear chemistry deals with radioactivity, nuclear processes, and properties. It has applications in nuclear energy, radiotherapy, and food preservation, among others.
Environmental Chemistry: Environmental chemistry explores the components of the environment and studies the impact of human activities on it. It plays a crucial role in improving and protecting the environment against pollution.
Examples and Numericals
Analytical Chemistry: Analytical chemistry involves the separation and analysis of substances to identify their components qualitatively and quantitatively. It finds application in various fields, including food, water, and clinical analysis.
Chemistry is an ever-evolving and dynamic field that has profoundly shaped our world. From everyday products to significant scientific breakthroughs, its influence is evident. As we continue to explore and understand the intricacies of matter, it is essential to balance progress with responsible and sustainable practices to safeguard our environment and enrich our lives further.
Basic Definitions
Matter: Matter is defined as anything that has mass and occupies space. It encompasses all physical substances, including living organisms, objects, and materials around us. In chemistry, we study various forms of matter that exist in three physical states: solid, liquid, and gas.
Substance: A piece of matter in its pure form is termed as a substance. Every substance has a fixed composition and specific properties or characteristics that distinguish it from other substances. Substances can be elements or compounds.
Mixture: Impure matter is called a mixture, which is formed when two or more elements or compounds physically combine without a fixed ratio. The components of a mixture retain their individual properties and can be separated by physical methods, such as distillation, filtration, or evaporation. Mixtures can be classified as homogeneous (uniform composition) or heterogeneous (non-uniform composition).
Physical Properties: Physical properties are associated with the physical state of a substance and do not involve any change in its chemical composition. Examples include color, smell, taste, hardness, shape of crystals, solubility, and melting or boiling points. Physical changes involve only changes in the physical state of matter, not its chemical composition.
Chemical Properties: Chemical properties depend on the composition of the substance. When a substance undergoes a chemical change, its composition changes, and new substances are formed. Examples of chemical properties include reactivity, flammability, and the ability to undergo specific chemical reactions.
Empirical Formula
- The empirical formula is the simplest whole number ratio of atoms present in a compound.
- It is determined by knowing the percentage composition of the compound.
- For example, silica (sand) has the empirical formula SiO, and glucose has the empirical formula CH2O.
Molecular Formula
- The molecular formula represents the actual number of atoms of each element present in a molecule of a compound.
- It is derived from the empirical formula by multiplying the subscripts by a whole number (n) that represents the number of empirical formula units in the molecule.
- For example, the molecular formula of benzene is C6H6, which is derived from its empirical formula CH.
Formula Unit (for Ionic Compounds)
- Ionic compounds exist in three-dimensional network forms.
- The formula unit is the simplest whole number ratio of ions present in the ionic compound.
- Ionic compounds have only empirical formulae.
- For example, the formula unit of common salt (NaCl) consists of one Na+ ion and one Cl- ion.
- Molecular Mass and Formula Mass:
The molecular mass is the sum of atomic masses of all the atoms present in one molecule of a molecular substance.
The formula mass is the sum of atomic masses of all the atoms present in one formula unit of an ionic substance.
For example, the molecular mass of water (H2O) is 18 amu, and the formula mass of sodium chloride (NaCl) is 58.5 amu.
Mole and Avogadro’s Number
A mole is defined as the amount (mass) of a substance that contains 6.02 × 10^23 particles (atoms, molecules, or formula units).
Avogadro’s Number (6.02 × 10^23) represents the collection of particles in one mole of a substance.
Mole-Mass Calculations:
These calculations involve converting the mass of a substance to the number of moles using the molar mass (mass of 1 mole of the substance). The relationship between mass, number of moles, and molar mass is given by the equation: Number of moles = Mass / Molar mass.
Mole-Particle Calculations
In these calculations, the number of moles of a substance is calculated from the given number of particles (atoms, molecules, or formula units).
The relationship between the number of particles, number of moles, and Avogadro’s number is given by the equation:
Number of moles = Number of particles / Avogadro’s number
Overall, these concepts and calculations help chemists understand and quantify the composition of different substances and molecules, facilitating various chemical reactions and research in the field of chemistry.